Apparatus or method for controlling tape speed

ABSTRACT

On the occasion of stopping the tape running at a high speed, a winding radius of the tape supply reel is detected to set the tape deceleration rate (a) on the basis of the detected winding radius of the supply reel. After the tape running speed is decelerated up to the allowable speed VL in the predetermined deceleration rate (a), the tape is stopped by effectuating the brake. Thereby, the tape can be driven at the speed higher than the allowable speed VL without generating any damage, enabling reduction of time required for the fast-forward/rewind operation. This can improve application flexibility by providing a couple of tape running modes at the first high speed V1 which is higher than the allowable speed VL and the second high speed V2 which is lower than the allowable speed VL. In addition, running of the tape can be ceased within the predetermined time t from the input of the stop command signal by specifying the maximum speed Vmax depending on the preset deceleration rate (a) and limiting the tape running speed with the maximum speed Vmax.

This application is a continuation application of co-pending applicationU.S. Ser. No. 08/708,097, filed Aug. 27, 199, U.S. Pat. No. 5,839,683.

BACKGROUND OF THE INVENTION

The present invention relates to a tape running apparatus through thedrive of reels to wind up the tape to a take-up reel from a tape supplyreel and particularly to a tape running apparatus which has reduced thefast-forward/rewind time without giving any damage on the tape runningmechanism and the tape itself.

It has been proposed to implement speed control by setting the allowablespeed determined by the tape running apparatus as the target speed.According to this method, since the tape is running at the allowablespeed which does not give any damage thereon even if the current taperunning speed is braked, the tape is not damaged if the running isbraked immediately, responding to input of the stop command signal. Thatis, the tape can be run at a high speed without generation of damage.

However, the tape running method explained above has a problem thatcharacteristics of motor cannot be utilized in the full-scale becausethe speed control is implemented at the allowable speed not giving anydamage on the tape.

SUMMARY OF THE INVENTION

It is an object of the present invention to realize running of the tapeat the speed higher than the allowable speed without giving any damageon the tape in order to reduce the time required forfast-forward/rewind.

In view of attaining the object explained above, the tape runningapparatus of the present invention comprises a tape speed control meansfor running the tape at the speed Vn which is remarkably higher than theordinary playback (reproduction) speed, a velocity detecting means fordetecting the tape running speed V, a tape winding radius detectingmeans for detecting a winding radius value of the tape supply reel, adeceleration rate setting means for setting the deceleration rate (a)depending on the winding radius value of the supply reel detected by thewinding radius detecting means, a velocity decelerating means fordecelerating the tape speed in the deceleration rate (a) set dependingon the input of a stop command signal, and a running stop means forstopping the running of the tape when the tape speed V detected by thespeed detecting means becomes lower than the allowable speed VL afterthe stop command signal is inputted.

Moreover, the speed control means further comprises a first speedcontrol means for running the tape at the first high speed V1 higherthan the allowable speed VL, a second speed control means for runningthe tape at the second high speed V2 lower than the allowable speed VLand a speed changeover means for changing over the first and secondspeed control means depending on the input of a speed changeover commandsignal and is constituted to generate a speed changeover signal forchanging over the first and second high speed running means for eachinput of the high speed running command input while the tape is runningat the first high speed V1 or the second high speed V2.

In addition, a speed limiting means is also comprised to calculate aspeed variation rate ΔV(t) when the tape speed is decelerated by thedeceleration rate setting means in the deceleration rate (a) for thepredetermined time t in order to limit the speed Vn by setting an addedvalue of the speed variation rate ΔV(t) and the allowable speed VL or anadded value of the speed variation rate ΔV(t) and the second high speedV2 as the maximum running speed Vmax.

With the constitution explained above, a winding diameter of the supplyreel is detected and the deceleration rate (a) is set depending on thereel winding diameter detected. Therefore, the supply reel neversupplies the tape, during the deceleration of the speed, in such amountas cannot be wound by the take-up reel. After the tape running speed isdecelerated to the allowable speed or lower not giving any damage on thetape when it is braked, the tape running is stopped by the braking orthe like. Thereby, the tape is never damaged even when the tape runningat a higher speed is stopped. Therefore, problems regarding the taperunning at the speed higher than the allowable speed can be solved torealize further reduction of the time required for fast forward/rewindoperation.

Moreover, the constitution to change over the first and second highspeeds V1 and V2 for the control enables improvement in the applicationflexibility for tape positioning.

In addition, transition of the tape speed to the speed lower than theallowable speed can be completed within the predetermined time t fromthe input of the stop command signal or speed change-over command signaland thereby the time required for stop and transition time to eachrunning mode can be set by calculating speed variation rate at the timeof decelerating the speed in the deceleration rate (a) for only thepredetermined time t and then limiting the speed with the maximum speedpreset depending on such amount of speed change.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an embodiment of a tape runningapparatus of the present invention.

FIG. 2 is a graph showing relationship between winding radius value anddeceleration rate in the present invention.

FIG. 3 is a waveform diagram illustrating running stop operation of atape running apparatus of the present invention.

FIG. 4 is a waveform diagram illustrating running stop operation of atape running apparatus of the present invention.

FIG. 5 is a block diagram of the other embodiment of a tape runningapparatus of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of the present invention will be explained withreference to the block diagram of FIG. 1. In FIG. 1, the referencenumerals 1, 2 designate reels; 3, a tape; 4, 5, reel bases; 6, ameasuring instrument for measuring the rotating period Ts of the reelbase 4 from FG (Frequency Generator) pulse obtained in proportion torotation of the reel base 4; 7, a measuring instrument for measuring therotating period Tt of the reel base 5 from FG pulse obtained inproportion to rotation of the reel base 5; 8, 9, brakes; 10, a motor;11, a driving force transmitting means for transmitting a rotating droveforce of the motor 10 to the reel base 4 or reel base 5; 12, a measuringinstrument for measuring the rotating period Tc of the motor 10 from theFG pulse obtained in proportion to rotation of the motor 10; 13, awinding radius detecting means; 14, a velocity detecting means; 15, adeceleration rate setting means; 16, a control speed change-over means;17, a velocity error detecting means; 18, a PWM (pulse with modulationsignal) generator; 19, an integrator; 20, a motor driver; 21, a stopdiscriminating means; 22, a brake driving means; and T1, T2, inputterminals.

First, operations when the tape is running at the speed Vn will beexplained.

The motor 10 rotates to generate a driving force by receiving an outputsignal from a motor driver 20. A driving force of the motor 10 is thentransmitted, via the driving force transmitting means 11, to the reelbase 5 during the normal rotation or to the reel base 4 during theinverse rotation. Therefore, the tape 3 is wound by the reel 2 duringthe normal rotation or by the reel 1 during the inverse rotation. Inthis case, the rotating period of the reel base 4 is measured with themeasuring instrument 6, that of the reel base 5 with the measuringinstrument 7 and that of the motor 10 with the measuring instrument 12,respectively. The measured rotating period data of the reel bases 4,5and motor 10 are inputted to the winding radius detecting means 13 andvelocity detecting means 14.

The winding radius detecting means 13 detects the winding radius valuesRs, Rt of the reels 1, 2, for example, from the following equation (1).

    Rs=√S/(π·(1+(Tt/Ts).sup.2), Rt=√S/π·(1+(Ts/Tt).sup.2               (1)

However, S indicates a total winding area of the tape including the reelhub when it is observed from the upper side. Moreover, the velocitydetecting means 14 detects the running speed V of the tape, for example,from the following equation (2).

    V=2·πRt/Tt                                     (2)

The winding radius data Rs, Rt detected by the winding radius detectingmeans 13 are inputted to the velocity detecting means 14 anddeceleration rate setting means 15. Moreover, the speed data V detectedby the velocity detecting means 14 is then inputted to the velocityerror detecting means 17 and stop discriminating means 21.

In the deceleration rate setting means 15, the deceleration rate (a)which does not generate looseness of tape at the time of deceleration ofspeed is set by the winding radius data Rs or Rt inputted from thewinding radius detecting means 13. Here, for the running at thedeceleration rate not generating looseness of the tape, the decelerationrate (a) of the tape take-up reel to be controlled must be set to thespeed lower than the speed decelerated by the load torque of the tapesupply reel freed from control. Namely, the deceleration rate (a) [mm/s²] is set by the following equation (3). In the equation (3), T, R, Iindicate respectively a load torque [grf/cm], winding radius value [mm]and inertia moment [gr/mm² ] of the tape supply reel. Here, the loadtorque T, inertia moment I must be obtained previously by themeasurement or the like. In addition, the tape supply side is located inthe side of reel 1 during the normal rotation or in the side of reel 2during the inverse rotation. A relationship between the winding radiulsvalue set by the equation (3) and the deceleration rate (a) is shown inFIG. 2. Where, both sides of equal mark are set equal in the equation(3).

    a=T·R/I                                           (3)

The deceleration rate (a) set by the deceleration rate setting means 15is inputted by the control speed change-over means 16. In the controlspeed change-over means 16, the control speed Vn is set by the speedchange-over signal inputted via the terminal T2. The preset controlspeed Vn is inputted to the velocity error detecting mans 17. In thisvelocity error detecting means 17, an error element between the speeddata V detected by the velocity detecting means 14 and the control speedVn set by the control speed change-over means 16 is calculated. The taperunning speed V is caused to follow up the control speed Vn by feedingback the velocity error element calculated by the velocity errordetecting means 17 to the motor 10 via the PWM generator 18, integrator19 and motor driver 20.

Next, the operation for stopping the tape from the running speed Vn willthen be explained with reference to the waveform diagrams of FIG. 3 and.FIG. 4.

For stopping the running of tape, a stop signal is first inputted to thecontrol speed change-over means 16 and stop discriminating means 21 viathe terminal T1. In the control speed change-over means 16, subtractionof the control speed Vn is started with input of the stop signal. Here,amount of subtraction of the control speed Vn per unit time isproportional to the deceleration rate (a) inputted by the decelerationrate setting means. Therefore, the control speed Vn changes with aninclination corresponding to the deceleration rate (a). Accordingly, therunning speed V follows up the control speed Vn and is reduced in thedeceleration rate (a). On the other hand, after the stop signal isinputted, the stop discriminating means 21 outputs the brake permittingsignal, upon detection that the speed data V inputted from the velocitydetecting means 14 becomes lower than the allowable speed VL. The brakepermitting signal outputted from the stop discriminating means 21 isthen inputted to the brake driving means 22. This brake driving means 22drives the brakes 8, 9 with the brake permitting signal from the stopdiscriminating means 21 to stop the running of the tape.

Therefore, when the control speed Vn outputted from the control speedchange-over means 16 in above explanation is equal to the speed V1 whichis higher than the allowable speed VL, the stop signal is inputted andthe speed is decelerated to the speed VL from the speed V1 as shown inFIG. 3. Thereafter, the stop discriminating means 21 outputs the brakepermitting signal to stop the running of the tape. Here, as shown inFIG. 2, since the deceleration rate changes to a1, a2, a3 as the windingradius of the supply reel changes to R1, R2, R3, the brake timing forrespective winding radius is different as shown in FIG. 3.

Moreover, when the control speed Vn is equal to the speed V2 which islower than the allowable speed VL, the brake permitting signal isoutputted from the stop discriminating means 21 simultaneously with theinput of the stop signal as in the case of the related art as shown inFIG. 4 to stop the running of the tape.

According to the embodiment explained above, when the tape is running atthe speed V1 which is higher than the allowable speed VL, the timerequired for fast-forward/rewind operation can be reduced remarkably,but since the tape stops after the running speed thereof is deceleratedto the speed VL before the stoppage during the stop operation,positioning of the tape is difficult and it is very inconvenient forretrieval of the recorded contents. Moreover, when the tape is runningat the speed V2 which is lower than the allowable speed VL, since thetape stops simultaneously with input of the stop signal, it isconvenient for retrieval of the recorded contents but the time requiredfor fast-forward/rewind operation is not reduced as in the case of therelated art.

Therefore, application flexibility can be improved for various purposesby changing over the tape running speed to the speed V1 and V2 with thecontrol speed change-over means 16.

In addition, the change-over operation can be simplified and applicationflexibility can further be improved by changing over the speed V1 andV2, for example, when the fast-forward button is depressed during thefast-forward operation or when the rewind button is depressed during therewind operation.

However, change-over of the speed to V2 from V1 decelerates the controlspeed to the speed V2 with the deceleration rate (a).

Next, another embodiment of the present invention will be explained withreference to the block diagram of FIG. 5. In FIG. 5, the referencenumeral 23 designates a speed variation rate calculating means and 24, aspeed limiting means. However, operations of the block designated by thesame reference numeral as that in the block diagram of FIG. 1 are sameas those as explained above.

As in the case of the above explanation, the deceleration rate (a) setby the deceleration rate setting means 15 is inputted to the speedvariation rate calculating means 23. Moreover, the control speed Vn setby the control speed change-over means 16 is inputted to the speedlimiting means 24. The speed variation rate calculating means 23calculates a speed variation rate ΔV(t) at the time t when the speed isdecelerated in the deceleration rate (a) inputted from the decelerationrate setting means 15. The speed variation rate ΔV(t) calculated in thespeed variation rate calculating means 23 is then inputted to the speedlimiting means 24. The speed limiting means 24 outputs, when the controlspeed Vn inputted from the control speed change-over means 16 is lowerthan the maximum speed Vmax which is obtained by adding thepredetermined speed Vm to the speed variation rate ΔV(t) inputted fromthe speed variation rate calculating means 23, the control speed Vn asthe new control speed Vn' and also outputs the maximum speed Vmax as thenew control speed Vn' when the control speed Vn is higher than themaximum speed Vmax. The control speed Vn' outputted from the speedlimiting means 24 is then inputted to the velocity error detecting means17. Hereinafter, the tape running speed V follows up the control speedVn' as the case explained above.

Therefore, in the case of stopping the running of the tape, the timeuntil actual stop from input of the stop signal can be set within t bycalculating the maximum speed Vmax in the speed limiting means 24considering the predetermined speed Vm as the allowable speed VL andthen immediately effectuating the brake when it is detected that thetape speed becomes equal to the allowable speed VL in the stopdiscriminating means 21.

Moreover, as explained previously, when the tape speed is changed overbetween the speed V1 and V2 (V1>V2), deceleration to the speed V2 fromthe speed V1 can be completed within the time t by calculating themaximum speed Vmax considering the predetermined speed Vm as the speedV2.

In above embodiment, the tape is supplied from one reel and is thentaken up by the other reel, but the present invention does not limit thebehavior of the tape between both reels and existence of the cassette.For instance, the present invention can obviously be applied to thefast-forward /rewind operation by the reel drive of a helical scanningtype VTR utilizing the rotary head, DAT, digital data recorder, cassettetype tape recorder utilizing the fixed head, open reel type taperecorder and digital data recorder or the like.

Moreover, in above embodiment, the tape running at the speed V1 which isremarkably higher than the ordinary playback speed is stopped or thetape running speed V1 is changed over to the speed V2. However, thepresent invention is not limited thereto and does not give anyparticular limitation on the speed so long as it is remarkably higherthan the ordinary playback speed. For instance, the present inventioncan also be applied to the system where the tape running speed iscontrolled by the rotating speed of the take-up reel.

As explained above, according to the present invention, since the tapeis stopped after it is decelerated to the allowable speed VL before itstops, the tape can be run at the speed higher than the allowable speedVL and the time required for the fast-forward/rewind operation can bereduced to a large extent without giving any damage to the tape.

In addition, a couple of running modes provided in the speed V1 which ishigher than the allowable speed VL and the speed V2 which is lower thanthe allowable speed VL enables selective application depending on thepurposes and also improves application flexibility.

Furthermore, since the maximum speed is limited depending on the presetdeceleration rate (a), the time required until the tape tops and thedecelerating operation until the desired speed Vm can be completedwithin the time t.

We claim:
 1. A tape speed control apparatus based on a reel drive fortaking up a tape to a take-up reel from a supply reel, comprising:aservo circuit which causes the tape to run either at a first speedhigher than a preset speed, or at a second speed lower than said presetspeed in response to input of a speed change-over command signal;wherein both said first speed and second speed are higher than anordinary playback speed; a speed detector which detects a current tapespeed; a calculator which calculates a data representing a woundtape-quantity on the supply reel; a decelerator which decelerates thetape speed at a rate based on said data in response to a stop commandsignal; and a brake which stops the tape when the current tape speeddetected by said speed detector is lower than said preset speed.
 2. Atape speed control method based on a reel drive for taking up a tape toa take-up reel from a supply reel, comprising:causing the tape to runeither at a first speed higher than a preset speed, or at a second speedlower than said preset speed in response to input of a speed change-overcommand signal; wherein both said first speed and second speed arehigher than an ordinary playback speed; detecting a current tape speed;calculating a data representing a wound tape-quantity on the supplyreel; decelerating the tape speed at a rate based on said data inresponse to a stop command signal; and stopping the tape when thedetected current tape speed is lower than said preset speed.